The Influence of Milling Time and $\hbox{ZrB}_{2}$ Addition on the Superconducting Properties of $\hbox{MgB}_{2}$

High-energy ball milling is generally used in granular materials to increase grain connectivity and densification. In this study, different high-energy ball milling times were investigated to optimize the MgB2 superconducting properties in samples with added ZrB2. The objectives of this addition were to modify the Mg planes and to create crystalline defects in the superconducting matrix that can act as pinning centers. We observed the behavior of the dopant on the superconducting properties, and found the optimal ball milling time of 300 min improved .ic in high magnetic field and H
_irr
from 7.2 to 10.0 T at 4.2 K.